Carbon nanotubes (CNT) are tube-shaped structures, and have extremely high electrical conductivity, very small diameters, and a tip-surface area near the theoretical limit. Thus, carbon nanotubes can transmit an extremely high electrical current and can be used to make cathode emitters.
One method for making carbon nanotubes based cathode emitters and assembling the carbon nanotubes in field emission devices is screen-printing. The method includes steps: (a) preparing printable carbon nanotube slurry, which usually includes carbon nanotubes, organic carrier, glass powder and organic solvent; and (b) providing cathode electrodes and forming patterned cathode emitters on surfaces of the cathode electrodes by printing using a screen. The screen-printing process is low in cost and can be easily operated. However, the mesh of the screen can be blocked by particles of the carbon nanotube slurry. Thus, the cathode emitters have trouble in forming a pattern having a size less than 100 microns using the screen-printing method.
What is needed, therefore, is to provide a carbon nanotube slurry and a method for making cathode emitters to overcome the above-described shortcomings.